Caught in Hillary Rodham Clinton's perpetual shadow, Joe Biden is working to boost his political profile among key Democratic voting blocs, a move that could help the vice president fashion himself as a more liberal alternative in the 2016 presidential race.

Businessman David Perdue has defeated longtime Rep. Jack Kingston in the Republican runoff for Georgia's U.S. Senate nomination, setting up a matchup against Democratic nominee Michelle Nunn that will help determine which party controls the Senate for the final years of the Obama administration.